For molecular biological characterization of the effects of Uwhangchungsimwon (UC) on the expression of nitric oxide synthase (NOS) gene and cell adhesion-regulating gene, vascular cell adhesion molecule-1 (VCAM-1), the human endothelial cell line (ECV304) was treated with the extract of UC and transcription of genes was examined using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. UC showed a transcription-activating effect on the NOS gene and a suppressing effect on the VCAM-1 gene in human endothelial cells, and these effects were found in a dose- and time-dependent manner. Down-regulation of VCAM-1 expression by UC was directly mediated by increased nitric oxide (NO) production, which was associated with increased NOS gene transcription. This study strongly suggests that the clinical effects of UC on stroke might be derived at least in part from its ability to induce NOS expression, which was followed by significant reduction of VCAM-1 expression. [ABSTRACT FROM AUTHOR]